Intrusion and fire detection system

ABSTRACT

A burglary and fire detection system in which sensors detect an intrusion into the space to be protected and transmit signals to logical control circuitry. After the signals from the sensors have been processed by the circuitry an alarm condition is sounded and/or appropriate authorities are notified. The system is set with an exit door in open position, and no alarm is transmitted for as long as the door remains open. An alarm is first transmitted after the door has been closed and then reopened.

2/53 511 xza lzc 3,634,846 2 5130 2017 72 Inventor Ma y x z 5, 7 R340/221 X (10; N X 100 X 3/3 D 340/276 [21] Appl. No. 81%., A 5. .w1.-.- 340/274 [22] Filed Apr. 9,1969 2,250,828 7/1941 340/274 PatentedJan. 11, 1972 3,286,250 l 1/1966 Teitelbaum 340/274 7 PrimaryExaminer-Thomas B. Habecker s4 INTRUSION AND FIRE DETEcnoN SYSTEM 12Claims, 4 Drawing Figs.

52 us. c1 340/274, ABSTRACT: A burglary and fire detection system inwhich 340/221 sensors detect an intrusion into the space to be protectedand [51] lnt.Cl .1 .G08bl9/00, transmit signals to logical controlcircuitry. Alter the signals 00% 13/08 from the sensors have beenprocessed by the circuitry an Field 0! Search 340/274, alarm conditionis sounded and/or appropriate authorities are 276, 221 notified.

The system is set with an exit door in open position, andno 1 [56]Rderences Cited alarm is transmitted for as long as the door remainsopen. An UNITED STATES PATENTS alarm is first transmitted after the doorhas been closed and 1 2,701,374 2/1955 Meats. 3 0/27 reopened-Waiver-a...

FLASH.L1GHT STEADY LIGHT FLOOD LIGHTS AUDIO RECORD. 7" TV RECORD. 68 fPHOTO CAM.

PATENTEU m1 1 I972 SHEET 1 [1F 2 as 24 I )1 FRONTDOOR SENSOR J1 DELAY i36 3 CONTROL 3o SYSTEM ON-OFF swncu 7 AND 46 SWITCHING WINDOW SENSORCIRCUIT A27 AUXILJDOOR SENSOR r 48 4 I A A A VIBRATION SENSOR 38 TEMP.SENSOR 40 SMOKE SENSOR INVENTOR. 4a CHEMICAL SENSOR Wfy POLICE INVENTORDE LAY SHEET 2 [IF 2 ISO DELAY zoo PATENTEUJANIHQYZ Nov INTRUSION ANDFIRE DETECTION SYSTEM BACKGROUND OFTI-IE INVENTION In the past, systemsfor the detection of intrusion into premises by burglars were complex indesign, difficult to operate, and uneconomical to manufacture. Pastsystems have been particularly difiicult to operate by the owner of thepremises or the authorized personnel designated by the owner to enterthe premises. In some systems, the owner would be compelled, forexample, to trigger the alarm each time he entered the premises. Inorder to prevent the alarm from sounding too long, he would then berequired to rush to a control box into which he would insert a key forthe purpose of tuming off the alarm. In other cases, the system hadprovision for allowing the owner a short period of time to turn the keyin the control box before the alarm would sound. In such a systemhowever, the owner would be required to rush out of the premises'once heset the alarm preparatory to leaving the premises. Systems are also inuse in which a control key is mounted directly onto the door and permitthe owner to turri on and off the alarm from the outside of thepremises. Such design does not require the owner to rush in his actionsfor operating the alarm, but at the same time, it exposes the controlkey to the potential burglar who may then tamper with the keylock at hisleisure. Furthermore, if a time delay was included in any of the systemsto give the owner time for carrying out any one of the operationsassociated with the alarm system, such a delay would also prevail or beincurred when the burglar were to enter through a window, for example.This delay would then give the burglar an amount of time in which hecould disarm the alarm system. Such systems, moreover, do not lendthemselves well to fire protection because the time delays incurredcould result in severe damage to life and property. Thus, in a firedetection system, it is of the utmost importance that when a fire isonce detected, an alarm condition be registered immediately thereafter.

Accordingly, it is an object of the present invention to provide aburglar and fire detection system which will detect an intrusion or afire within premises to be protected without requiring special skills tooperate. It is also an object of the present invention to provide aburglar and fire detection system which will not require hurried actionsfor setting or turning off the system upon entering or leaving thepremises. It is a further object of the present invention to provide adetection system of the aforementioned character which will notifydirectly police or fire authorities in the event of an intrusion or firewithin the premises to be protected.

SUMMARY OF THE INVENTION A burglary and fire detection system in whichsensors are mounted directly on or in the proximity of windows, doorsand other openings of the premises to be protected. The sensors whentriggered or actuated transmit electrical signals to a control circuitwhich examines the signals and responds by immediately registering analarm condition or postponing the alarm condition for a predeterminedtime interval. The control circuit furthermore, determines from thesensor signals whether a burglar alarm condition or fire alarm conditionis to be registered. The control circuitry is in the form ofintercnnected relays or digital transistor circuits performing thelogical functions required by the control circuitry in carrying out itsdesignated task. The output signals from the control circuitry aretransmitted directly to a central station or police and fire stations.If the signals are transmitted to a central station, monitoringpersonnel at this location may, in turn, notify police or fireauthorities, as well as dispatch investigating personnel.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an isometric view of thespace to be protected through the burglar and tire detection arrangementof the present invention;

FIG. 2 is a functional block diagram of the arrangement for protectingthe premises in FIG. 1, and shows the control circuitry for processingthe signals derived from the sensors;

Hg. 3 is an electrical circuit diagram, in the deenergized state, of oneembodiment of the circuitry used in FIG. 2 for processing the sensorsignals and exercising the controlling functions;

FIG. 4 is a logical diagram of the embodiment of FIG. 3, and providesfor the substitution of electronic gates for electromechanical relays.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, andin particular to FIG. I, sensors are mounted directly onto the windows,doors and other openings through which the premises to be protected maybe penetrated. Thus, in a typical premises 10 to be protected, a window12 has mounted onto it sensors 14 and 16. These sensors detect when the.movable window frame is displaced so that the window becomes open afterhaving previously been shut. These sensors 14 and 16 will detect theopening of a sash window, for example, through movement of its upper orlower sections. The sensors 14, for example,will detect downwardmovement of the upper section 12a, whereas the sensor 16 will detectupward movement of the lower section 12b of the sash window 12. Thesesensors 14 and 16 may be simple mechanical switches with parts mountedon the movable and/or stationary frames of the window which becomeopened or closed depending upon the position of the window. Suchmechanical switches are well known in the art and will therefore not bedescribed further here. The sensors 14 and 16 may, on the other hand,also be in the form of magnetic switches with parts mounted on themovable and stationary frames of the window. These magnetic switches aredesigned so that when brought into the proximity of a magnetic field,the switch becomes actuated to either open or close a circuit. Forpractical application, a permanent magnet may, for example, be mountedon the movable frame and the switch itself be mounted on the fixedframe. The mounting is such that when the window is closed, thepermanent magnet lies directly in proximity of the magnetic-sensitiveswitch. Accordingly, when the window becomes opened and the permanentmagnet is thereby moved out of proximity of the switch on the stationaryframe, the switch transfers state and transmits a signal designating theopening of window through either opening or closing a circuit. Suchmagnetic-sensitive switches are also well known in the art and thereforerequire no further description. Aphotqelecgig n sgg m also be providedto detect intrusion through the window. In such an arrangement a lightsource on one side of window, for example, directs a light beam againsta photosensitive element located at the opposite side of the window.When this light beam becomes interrupted during an intrusion, a signalis transmitted from the photosensitive element and interpreted todesignate that the window has been opened. Photoelectric sensors of thischaracter are also very well known in practice and will therefore not befurther described. In conjunction with the sensors 14 and 16 whichdetect positional changes in the movable frames of the window, silverfoil 18 may be applied directly to the window glass 20 to detect whenthe Wed. Such conductive silver foil is in conventional use andaccordingly requires no further explanation here. It is thus seen, thatthrough the switches 14 and 16, and the conductive foil 20, the window12 may be entirely protected against intrusion.

The door 22 of the premises 10 to be protected may be similarly guardedagainst intrusion. A sensor 24 similar in construction to the sensors 14or 16 may be mounted with parts on the door and/or the door frame. Thus,if a magnetic switch as described above for the sensors 14 and I6 isselected, the permanent magnet is mounted onto the door, whereas themagnetic-sensitive switch is mounted onto the door frame and directly inproximity of the permanent magnet when the door is closed. If, in thisarrangement, the door becomes opened, a

permanent magnet is moved out of proximity of the magneticsensitiveswitch and a signal is transmitted, thereby, by the switch to designatethat the door has been opened. This same arrangement usedfor the door 22can also be used for the win-' dow 12 if the latter is a casement typeof window rather than a sash type. Thus, magnetic switches used for thesensor 14 and 16, for example, may be applied to either sash or casementwindows, and only a difference in mounting is involved in adapting theseswitches to one type of window or another. The sensor 24, furthermore,may be, similar to the sensors 14 and 16, a photoelectric sensor or asimple mechanical sensor as described above.

To protect the premises against intrusion by cutting directly throughthe door 22 without actually opening the door, a wired panel 22a may bemounted directly within the door or on one of the sides thereof. Such awired panel may consist of a base panel mounting of electricallyinsulting material upon which wire or conductive foil is laid upon thepanel in weaved or zigzag fashion. If the wire or conductive foil isthen cut at any point along its length, a circuit connected to the panelbecomes interrupted to designate a possible intrusion through the doorproper. A wired panel of this type may also be used on the floor of thepremises 10 directly inside of the door 22. In such a case the panel isin the form of a floor mat and cooperating with a conductive membernormally held separated or spaced form the wired mat. When an intruderthen opens the door 22 and steps onto the mat and the conductive member,a signal is transmitted designating the presence of the intruder. Insuch an arrangement the mat may \be used in place of the sensor 24. Matsof this type are also well known in the art.

To protect against penetration of the premises through the walls, flooror ceilings of the premises, wired panels as described above may also bemounted within the walls or directly on the wall surfaces. Similarly,wired panels may be mounted in this manner within or on the surface ofthe floors and ceilings. Any opening generated by an intruder througheither the walls, floors or ceilings, will then be detected through thewired panels. In lieu of the wired panels vibration sensors 44 may alsobe mounted directly onto the wall surfaces, floors or ceilings. In suchan arrangement any tampering with the walls, for example, will producemechanical vibrations which will actuate the vibration sensor andthereby transmit a signal designating that the walls are possibly beingbroken through.

For the purpose of protecting the premises 10 against fire, heatdetection sensorsjirpay be mounted at various locations mprcmises. Suchheat sensors may be of the conventional bimgtalliustrig form in which acircuit through the switch is either opened or closed depending upon thetemperature to which the .switch is subjected. These heat detectionsensors, for example, will open or close a circuit when the temperatureexceeds 135. In conjunction with such heat detectors, s ng deteclor wmay also be used. Such smoke detectors are in conventional use and willtransmit a signal when surrounded by smoke. This signal from the smokedetector can then be used to register a fire alarm condition eventhrough no fire has been in contact with the smoke detector housing.Fire detection can also be supplemented through the use of chemicaldevices 42 which sense conditions of the air or immediate 'environ niemhat are favorable to combustion. With such chemical devices,therefore, it is possible to detect a fire prior to its actualoccurrenceJjOften referred to as ionization type of fire detectors, heydetect the presence of smoke and combustion products in the earliest orincipient stages when gases alone are being produced by the combustion.

In accordance with the presentinvention, sensors are associated with thewindow 12, front door 22, side door 26, as well as the walls, floors andceilings of the premises 10 to be protected. When any of the windows,doors or walls of the premises, for example, are penetrated an alarmcondition is immediately registered. This same situation prevails whenany one of the fire detection sensors-becomes actuated. A differenttreatment, however, is applied to the front door 22 through which theowner of the premises or other authorized persons enter for the purposeof disarming the alarm and preventing the registering of an alarmcondition as a result of the opening of the door 22. Thus, when the door22 is opened after the system, in accordance with the present invention,has been set for operation, a predetermined time interval is allowedbetween the instant the door is opened and the instant that the alarmcondition is actually registered. This time interval allows theauthorized person to shut off or disarm the system after entering thepremises. The disarming process may be carried out through the turningof, for example, a key or rotating a coded disc similar to thecombination dial locks used in safes. Since an intruder would notpossess such a key or the knowledge of the code to be used inconjunction with the code disc, the intruder would not be in a positionto disarm the alarm. In the system of the present invention, the alarmcannot be shut off by the intruder once it has been registered ortriggered.

The different sensors associated with the windows, doors, walls,ceilings and floors are all connected to a control and switching circuit28. The latter identifies the origin of the signals as received from thesensors and will transmit an alarm signal 30 immediately upon actuationof any of the sensors other than the sensor 24 for the front door 22.When the sensor 24 associated with the front door 22 becomes actuated,the alarm signal 30 is delayed through a delay circuit 32. Thus, whenthe signal 34 is applied to the control and switching circuit 28 throughthe setting key switch or coded disc 36, and the sensor 24 is actuated,the alarm signal 30 passes through the delay circuit 32 and is therebydelayed for a predetermined time interval. The alarm signal in thiscase, however, is transmitted only when the door is opened a secondtime. The control circuit 28 notes the condition that when the door 22is opened for the first time, it is because the authorized persons areleaving the premises, and therefore no alarm signal is transmitted. Ifan intruder opens the door 22 it will be the second opening for thatdoor since the alarm has been set, and as a result an alarm signal willbe transmitted at that time. When, however, any of the window sensors14, door sensors 27, or vibration sensors 44 associated with the floors,ceilings or wa s are actua e an immediate intrusion can be implied andas a result the alarm signal 30 is transmitted directly from the outputterminal 46 of the control circuit 28. In this manner, the alarm signal30 is registered immediately and without delay. The control circuit 28,in accordance with the present invention, provides also an indicatingsignal 48 which indicates to the owner or user of this'system that allsensors are in their proper operating state, and that all windows anddoors are closed, as required, prior toleaving the premises. Thisindicating signal 48 may be transmitted, for example, to an indicatinglamp which, after the setting unit 36 has been actuated, notifies theuser or owner that he may leave the premises with the knowledge thatafter he closes the door 22 behind him, the' premises will be secureagainst intrusion and/or fire. With regard to the fire detection featureof the present invention, the alarm signal 30 will be derived from theterminal 46 immediately after the temperature sensors 38, smoke sensors40, or chemical sensors 42 have been actuated. Thus, the control andswitching circuit 28 performs several logical functions which transmitthe alarm signal 30 through either the delay 32 or the terminal 46,depending upon the states of the various intrusion or fire sensors. inaddition, the circuit 28 provides an indicating signal 48 which guidesthe user of the protective system in determining that all sensors in thesystem have been properly set prior to leaving the premises.

The detailed design and structure of the control and switching circuit28 is shown in an exemplary embodiment of FIG. 3, which is shown in thedeenergized state. The key switch 36 which may be used to either set orturn off the detection system, is a single pole, single throw keyswitch. Thus,

this switch may be operated through a simple turn of a conventional key,and is commercially available. The sensor 24 associated with the frontor main door 22 is in the form of a single pole, double throw magneticswitch which is magnetically actuated in a manner described above inrelation to magnetic switches. All of the window switches 14 and 16, theconductive foil 18, and additional door sensors 27 are all connected inseries to the coil of a relay 50. All heat detection sensors 38, smokesensor 40 and chemical devices 42, are moreover also connected in theseries circuit leading to the coil of the relay 50. The arrangement ofFIG. 3 is designed and adapted to conform to a closed-circuit system inwhich monitoring current continuously flows through the sensing devices.

When the key switch 36 is turned so as to set the system, and allwindows and doors are shut with the exception of the front or main door,the coil of the relay 50 is energized. If the front or main door throughwhich the owner is to leave the premises remains, furthermore, in theopen position when the key switch 36 is closed, the relay 52 becomesenergized. This results from the condition that the magnetic switch 24on the front or main door forms a closed circuit between the coil of therelay 52 and the voltage source 54. When the relay 52 is thus energized,the indicating lamp 56 is energized through the voltage signal 48arising from the condition that both relays 50 and 52 are energizedsimultaneously. Thus, the indicating signal 48 arises, as noted above,only when all windows and doors, except the front door, are closed andall sensors are in their operative states. The indicating signal 48 andindicating lamp 56 energized by this signal thereby provide the owner oruser of the system with an indication that when he closes the front doorbehind him the premises will be protected. Once the owner does leavethrough the front door 22 and the latter becomes closed, the relay 52becomes released as the magnetic switch 24 transfers positions. When themovable contact of the switch 24 reaches the position shown in thedrawing, the relay 52 has been released or deenergized and the relay 58becomes energized. At the same time, the indicating lamp 56 no longerlights since the relay 52 has become deenergized. This is a desirablefeature which extends the operating life of the indicating lamp 56,since there is no need for maintaining this lamp lighted within thepremises after the latter have become fully secured, and the owner hasleft. If now, any of the series-connected sensors on the windows ordoors, for example, are opened, the relay 50 becomes deenergized and aclosed circuit is formed by the pole 50a between the junction point orcircuit point 30 and the terminal 36a at the output of the key switch.Since the latter is in closed or set position, a voltage appears at thecircuit point 30 and is available for registering an alarm condition.This alarm condition, therefore, appears immediately upon interruptionof the monitoring current through actuation of any one of the sensorsfrom its normal operating state. This condition also applies to the firesensors 38, 40, 42 which are connected in closed series circuit with thedoor and window sensors. It is also often to advantage to install panicbuttons or switches 39 which may be hand or foot actuated to transmit analarm. Thus, if a pushbutton 39 is installed at the bedside of a personwithin the premises to be protected such person can immediately transmitan alarm signal by depressing the pushbutton in the event of a fire orburglary. At the same time, the switches 39 can be in the form offoot-operated switches distributed throughout the premises and connectedin series to be operated when an emergency condition arises.

Consequently in the absence of an intrusion or fire, the relays 50 and58 are energized and no alarm signal appears at the circuit point 30.The relay 58 has its coil connected directly to the pole 58b whichleads, through its stationary contact, to the terminal or circuit point36a. As a result, the relay coil 58 remains energized once it has acurrent pulse applied to it. Accordingly, when the owner returns to openthe premises and the magnetic switch is transferred to the positionopposite to that shown in the drawing, the coil of the relay 58 remainsenergized through the contact 58b. At the same time,

the relay 52 becomes energized since the door 22 has become opened andthe switch 24 has correspondingly changed state. With the relays 52 and48 both energized simultaneously, a voltage signal is transmitted fromcircuit point 36a, through the closed contacts 58b and 52b, and appliedto the time delay circuit 32. it is to be noted that once the relay 52is energized upon reentering the premises through the front door, itremains energized even if the front door were to be again closed. Thiscondition results from the interconnection of the pole or movablecontact 52a with the moveable contact 58a leading to the circuit point360. Thus, as a result of the relay 58 being in the energized state, thecoil of the relay 52 is fed with current through the circuit of the twocontacts 52a and 58a and the relay 52 thereby continues to remainenergized regardless of the position of the switch 24. To prevent theregistering of an alarm condition due to the resulting voltage appliedat the terminal 320, it is necessary to interrupt the circuit by turningthe key switch 36, before the expiration of the time interval determinedby the time delay 32. if the key switch is not opened before this timeinterval, an alarm signal 30 appears.

The alarm signal 30 may be applied directly to an alarm device such asbells 60, a siren 62, or horn 64. Such audible alarm devices serve toscare the intruder and induce him to leave the premises without delay.While the use of such alarm devices aid in preventing a burglary frombeing fully carried out after the burglar has intruded the protectedpremises, they do not function to aid in catching the burglar. Thus,after the burglar hears the alarm sounds, he may leave the premises sorapidly that police authorities may not arrive in time to intercept him,provided such police authorities have been summoned by someone who hasheard the alarm.

For the purpose of notifying police authorities at the earliestopportunity after an intrusion has occurred, it is desirable to transmitthe alarm signal 30 directly to the police station 66 serving thepremises. Such transmission of the alarm signal 30 to a remotely locatedpolice station may be accomplished over telephone lines which may, forexample, be leased from the m company. At the same time, auxiliarytelephone transmission apparatus 68 may be used to avoid the requirementof using a separate and independent telephone line between the premisesto be protected and the police station. Such an auxiliary transmissiondevice 68 may be in the, form of, for example, a conventional telephonedialing unit which, upon being actuated by the alarm signal 30, dialsthd telephone number of the police station and then transmits a recordedmessage giving the location of the premises in conjunction with thestatement that an intrusion has occurred into] the premises. Suchauxiliary transmission devices 68 are well known in the an and willtherefore not be described here further. If the system is selected inwhich the alarm signal 30 is transmitted directly to the police station,it may be desired to disconnect the audio-alarm device 60, 62 and 64 forthe purpose of'realizing a silent alarm so that the intruder is notinformed that the police authorities have been notified of theintrusion. Such a system arrangement is desirable when the owner leavesthe premises vacant behind him. When, however, the owner is within thepremises and wishes that the burglary and tire detection system, of thepresent invention, be fully operative while the owner is asleep duringthe night, for example, it may be desirably to have the alarm signal 30transmitted to the police station and, at the same time, to theaudioalarm devices. In this manner, protection of the persons within thepremises is obtained at the expense of not catching the intruder. Thus,when the intruder hears that such an alarm has been registered, it islikely that he will try to escape by leaving the premises without delay,and thereby have not sufficient time available to do bodily harm to theinhabitants of the premises.

To permit selected connecting and disconnecting of the audio devices, aswell as the police station to and from the alarm signal 30, independentselector switches 70 are provided. These selector switches may beindependently and separately actuated to permit any desired combinationof connections between the alarm signal 30 and the audio-alarm devicesas well as the police station. In addition to the audioalarm devices 60,62 and 64, it may also be desirable-to apply the alarm signal 30 tovisual-alarm devices such as a flashing red light 72, a steady red light74, flood lights 76, and a television tape recorder 78. The flashinglight 72 may be mounted directly at a window of the premises for thepurpose of informing neighbors and bypassers to summon authorities toinvestigate the premises. The steady light 74, on the other hand, may beused in the same or another window to indicate to the owner that thealarm has been triggered from within for whatever reason. Thus, afterthe owner has set the alarm and closed the front exit door behind him,he may wish to be assured that the alarm was not triggered during theprocess of closing the door. By glancing afterward toward the window inwhich the steady lamp 74 is located, he may be reassured that the alarmwas not triggered if no such steady light signal appears. Such a steadylight may be used in conjunction with the silent alarm to the policestation, since such a steady light signal is not likely to scare off theintruder, while the premises are vacant and in the absence ofaudio-alarm devices. Flood lights 76, however,. may be used inconjunction with such audio-alarm devices mentioned above, to furtherscare the intruder, if this particular function is desired. If, forexample, it is intended to have the intruder leave as rapidly as onewould wish, it is likely that the sudden appearance of flood lights inaddition to the sounding of the audio-alarm devices will contribute muchto this desired result.

The alarm signal 30 may be also transmitted to a television camera whichmay or may not operate in conjunction with a television tape recorder.When using such a television system 78, the intruder may by visuallyobserved from the moment that the camera is switched to its operativestate, if a remotely located television receiver is used for the purposeof monitoring the premises. To avoid the necessity of continuouslymonitoring the premises with a television receiver over closed circuit,for example, a television tape recording unit may be used in conjunctionwith the television camera. Such a television tape recording unit willrecord the scene observed by the camera and thereby provide a permanentrecord for subsequent playback. Such an arrangement may be desirable insubsequent court trails, for example, arising out of the intrusion.Since such television equipment is usually costly, a photographic ormotion picture camera 80 may be employed in its place. The camera 80would be triggered by the alarm signal 30 in,a manner similar to thetelevision system, and upon such actuation by the alarm signal 30, thephotographic camera may be arranged to take a picture or a plurality ofpictures of the premises and thereby also of the intruder. To furtherrecord the circumstances of any intrusion, the alarm signal 30 may alsobe applied to an audio recorder 82 which may be in the form of amagnetic tape a 186 record, a wire recorder, or one of the conventionalsound recording devices. By actuating the proper ones of these selectorswitches 70, it is possible to connect, disconnect and combine anynumber of the preceding visual and audio devices.

' In lieu of transmitting the alarm signal 30 directly to the policestation 66, it may be of advantage in particular instances, to transmitthis alarm signal to a central monitoring station 84 prior to notifyingthe police. Thus, in a densely populated area, for example, it may notbe practical to have a large number of protected premises communicatedirectly with the police. in such a case, a central monitoring station84 may serve as an intermediary between the protected premises and thepolice. Such an arrangement, permits any number of premises to beprotected, while requiring only a single line of communication betweenthe central station and the police. The central monitoring station 84also affords the opportunity of investigating any alarm so that thepolice will not be notified in the event that a false alarm hasoccurred. When many premises to be protected are, furthermore, closelylocated such as in a large apartment house, and the police station isrelatively distantly located from such premises, the central monitoringstation 84, may be used to reduce the total length of communicationlines that would ordinarily be required between the police and thepremises in the absence of the central station 84. The latter can alsoserve directly as a source of armed guards which are dispatched with orwithout police authorities. The alarm signal 30 may be used to actuateeither an open circuit or a closed circuit communicating with thepolice.

ln particular installations it may be desired to provide a fire alarmsystem independent of the burglar alarm system. in such an independentfire alarm system, a fire alarm signal can'be transmitted directly tothe fire station, instead of communicating such a signal via the police.Such a system results in earlier notification of the fire department andthereby diminishes the potential damage to the protected premises. lf aclosed-circuit fire alarm system is to be independently installed forthis pur' pose, the coil of a relay 86 becomes energized directly fromthe voltage source 54 through closed-circuit contacts ,14a, 16a and 18awhich are identical to the contacts 14, 16 and 18, respectively,described above for the use of firedetection. Provided that the pole ormovable contact 86a of the relay 86 is in the position shown in thedrawing, the fire detection system has been actuated through the openingof any of the contacts associated with the fire detection sensors,resulting in the deenergizing of the relay 86. In this state of therelay 86, therefore, a fire alarm signal 88 is transmitted from the poleor contact 86a. This alarm signal 88 may be transmitted directly to thefire department and independently of the police station. if, on theother hand, the fire detection sensors has not been actuated, the relay86 remains energized and the signal 88 is inhibited from beingtransmitted to the fire department. By connecting the independent firealarm circuit directly to the voltage source 54, the fire detectioncircuit may be operative at all times, even when the burglar detectionsystem is inoperative or has been turned off. The fire detection system90 is the open-circuit equivalent of the fire detection circuit 85.Thus, if an open-circuit system is to be used, open-circuit contacts38b, 40b and 42b may be connected in parallel to transmit the fire alarmsignal 92. The circuit contacts 38b, 40b 42b are associated with thefire detection sensors and become closed when their respective sensorsbecome actuated. In this manner, these contacts 38b, 40b and 42b servethe same function as the contacts 38a, 40a and 40b with the onlyexception that the latter are closed-circuit contacts whereas the formerare open-circuit contacts.

The voltage source 54 may be advantageously constructed by providing 'atransformer which steps down the utility supplied voltage of 1 10 volts,for example, to 6 volts suitable for transmitting power withoutrequiring'special protective power transmission lines. Through theuse ofa rectifier circuit 102 which may be of the conventional full-wave type,the 6 volts AC are converted to 6 volts DC and applied to a fixedcontact of a relay 104 which is energized directly by the l 10- voltline. The movable contact 1040 leads directly to the circuit point 54a,and will provide operating voltage derived from the transformer 100. Inthe event that a power failure occurs and the utility voltage is notavailable, the relay 104 becomes deenergized so that the movable contact104a transfers to the position in which it becomes connected to thebattery supply 106. Thus, this battery serves as a standby source ofpower which allows the burglar and fire detection system to remainoperative even under conditions of utility power failure, or theseverance of power lines by intruders or fire.

' The control circuit 28 may be synthesized through electronic logicalelements rather than electromechanically operating relays. An advantageof using electronic circuitry rather than relays resides in the featurethat the electronic circuitry may thereby be confined to a particularlysmall space. Thus, control circuit 28 shown in detail of FIG. 3 with theuse of relays, has the logical diagram shown in FIG. 4. For example, thelogical conditions to be satisfied by the circuitry of FIG. 3 is suchthat a signal output is applied to the input 32a of the time delay 32,when and only when the door associated with the switch 24 has beemopenedafter having been previously closed. Accordingly, a logical AND-gate 200is required to perform this logical function. One input to the AND gateis connected to the fixed terminal 24b of the switch 24, whereas theother input to the gate 200 is connected to the terminal 24a of thisswitch. When the premises have been once secured by the owner, and thefront door has been closed, a signal input will be applied to theAND-gate 200 from the terminal 24b. When returning, now, to reopen thedoor, the switch 24 transfers positions and a signal is applied to theAND-gate 200 from the terminal 24a. By means of the capacitor 202 astorage device is realized for remembering that the door had beenpreviously closed. Thus, the input of the gate 200 leading to thecontact 24b will be retained, for a period of time, even though switch24 transfers positions. With the two inputs both simultaneously in theon" state, a signal appears at the output of the gate 200 and istransmitted to the time delay 32. The latter is of the bistable type sothat once actuated by a pulse from the output 32a of the gate 200, itwill remain in the actuated state. Therefore, once actuated in thismanner, the time delay 32 will transmit a signal 30 for registering analarm after a predetermined time interval designed to give the ownersufficient time to disconnect or disarm the burglary detection system.Another condition which is to be met by the circuitry of FIG. 3, is thatthe indicating lamp 56 is to be turned on provided a signal istransmitted from the contact 24a, while a signal appears simultaneouslyat the circuit point 50c. This function is performed through theAND-gate 204 which has one input leading to the contact 24a, and anotherinput leading to the series connected contact for windows, doors, andfire detectors, which terminate in the circuit point 500. It is also acondition of the circuitry of FIG. 3 to register an alarm immediately,without delay, when the signal prevailing at circuit point 500 isinterrupted. after the front door had been closed for leaving thepremises in secured condition. This feature is realized through theAND-gate 206 which has one input leading to the contact 24b, and anotherinput leading to the circuit point 50c by way of inverter 208. Thelatter inverter is required since a signal input to the gate 206 isdesired when no signal appears at the circuit point 500. It is notnecessary to include the connection between the circuit point 36a andany of the AND gates, since an AND function is realized through theseries connection of the switch 36 and the switch 24. Thus, no signaloutputs may be realized from the contact 24a and 24b if the switch 36 isnot closed. The logical gates and inverter in FIG. 4 are of theconventional type known in the art. The arrangement of F IG. 3 may alsobe used to guard against the spoilage of food in a freezer powered fromthe same 1 lO-volt supply which maintains relay 104 energized. A signaldevice 150 in the form of a lamp or buzzer, for example, may be used toreport that the l l-volt power is inoperative. Thus when the relay 104becomes deenergized, contact 10412 connects the signal device 150 to thebattery 106. This feature is particularly useful in protecting contentsof freezers, and avoiding damages incurred from equipment which dependson the continuous operation of the l lO-volt power.

lclaim:

l. A method for arming an intrusion detection system and transmitting.an alarm upon an intrusion into an enclosed space, comprising the stepsof: opening said enclosed space a first time; activating said system andsetting said system to a first state while said space is open;inhibiting transmission of said alarm indefinitely while said enclosedspace is open for the first time from the instant that said system is insaid first state; closing said space and setting said system to a secondstate, said system being armed while in said second state; opening saidspace a second time and setting said system to a third state; andtransmitting said alarm signal a predetermined time interyaLs lgegyentto said second opening of said space while said system is in said thirdstate.

2. An arrangement for detecting intrusion into a predetermined enclosedspace comprising, in combination, at least one opening into said space;closure means for coverm g said opening; which means in proximity ofsaid opening and providing a first signal when said opening is uncoveredand a second signal when the opening is closed; signal-processing meanslinked with said switch means and having: first circuit means actuatedby said first signal when said opening is first uncovered, secondcircuit means actuated by said second signal when said opening iscovered after said first uncovering, third circuit means connected tosaid first circuit means and said second circuit means and actuated'bysaid first signal when said opening is uncovered a secondtimethereafter, and fourth circuit means connected to said third circuitmeans for emitting a third signal a predeterminedtirne interval.subsequent to said second uncovering of said opening, saidsignal-processing means inhibiting transmission of said third signalindependent of time from the instant that said first circuit means isactuated by said first signal to the instant that said second circuitmeans is actuated by said second signal upon closing said opening aftersaid first uncovering, said opening being uncovered during the intervalbetween said instant that said first circuit means is actuated by saidfirst signal and said instant that said second circuit means is actuatedby said second signal.

3. The arrangement as defined in claim 2 including firesensing meanswithin said space for sensing the rise and presence of a fire withinsaid space; and means within said signal-processing means and connectedto said fire-sensing means for emitting a signal immediately uponactuation of said fire-sensing means.

4. The arrangement as defined in claim 2 including setting meansoperatively connected to said signal-processing means for setting saidsignal-processing means into operative state prior to covering saidopening.

5. The arrangement as defined in claim 2 including at least oneadditional opening with means for covering the same; sensing meanscooperating with said additional opening for sensing when saidadditional opening is uncovered and covered by the covering means forsaid additional opening; and means in said signal-processing means foremitting a signal immediately upon uncovering of said additionalopening.

6. The arrangement as defined in claim 2 including indicating meansoperatively linked to said switch means for indicating the operativestate and said switch means.

7. The arrangement as defined in claim 2 including auxiliary sensingmeans for sensing penetration into said space with said openingremaining covered.

8. The arrangement as defined in claim 2 includingsound emitting meansoperatively connected to said signalprocessing means and actuated bysaid third signal.

9. The arrangement as defined in claim 2 including picture recordingmeans for recording the visual appearance of the in-; terior of saidspace.

10. The arrangement as defined in claim 2 including visual indicatingmeans operatively connected to said signal processing means and actuatedby said third signal.

11. The arrangement as defined in claim 2 including signaltransmittingmeans connected to said third signal-processing means for transmittingsaid third signal to a location remote from said space.

12. The arrangement as defined in claim 2 including manually operableswitching means within said space and linked to said signal-processingmeans, said signal-processing means emitting an undelayed signal whensaid switching means is manually actuated.

1. A method for arming an intrusion detection system and transmitting analarm upon an intrusion into an enclosed space, comprising the steps of:opening said enclosed space a first time; activating said system andsetting said system to a first state while said space is open;inhibiting transmission of said alarm indefinitely while said enclosedspace is open for the first time from the instant that said system is insaid first state; closing said space and setting said system to a secondstate, said system being armed while in said second state; opening saidspace a second time and setting said system to a third state; andtransmitting said alarm signal a predetermined time intErval subsequentto said second opening of said space while said system is in said thirdstate.
 2. An arrangement for detecting intrusion into a predeterminedenclosed space comprising, in combination, at least one opening intosaid space; closure means for covering said opening; which means inproximity of said opening and providing a first signal when said openingis uncovered and a second signal when the opening is closed;signal-processing means linked with said switch means and having: firstcircuit means actuated by said first signal when said opening is firstuncovered, second circuit means actuated by said second signal when saidopening is covered after said first uncovering, third circuit meansconnected to said first circuit means and said second circuit means andactuated by said first signal when said opening is uncovered a secondtime thereafter, and fourth circuit means connected to said thirdcircuit means for emitting a third signal a predetermined time intervalsubsequent to said second uncovering of said opening, saidsignal-processing means inhibiting transmission of said third signalindependent of time from the instant that said first circuit means isactuated by said first signal to the instant that said second circuitmeans is actuated by said second signal upon closing said opening aftersaid first uncovering, said opening being uncovered during the intervalbetween said instant that said first circuit means is actuated by saidfirst signal and said instant that said second circuit means is actuatedby said second signal.
 3. The arrangement as defined in claim 2including fire-sensing means within said space for sensing the rise andpresence of a fire within said space; and means within saidsignal-processing means and connected to said fire-sensing means foremitting a signal immediately upon actuation of said fire-sensing means.4. The arrangement as defined in claim 2 including setting meansoperatively connected to said signal-processing means for setting saidsignal-processing means into operative state prior to covering saidopening.
 5. The arrangement as defined in claim 2 including at least oneadditional opening with means for covering the same; sensing meanscooperating with said additional opening for sensing when saidadditional opening is uncovered and covered by the covering means forsaid additional opening; and means in said signal-processing means foremitting a signal immediately upon uncovering of said additionalopening.
 6. The arrangement as defined in claim 2 including indicatingmeans operatively linked to said switch means for indicating theoperative state and said switch means.
 7. The arrangement as defined inclaim 2 including auxiliary sensing means for sensing penetration intosaid space with said opening remaining covered.
 8. The arrangement asdefined in claim 2 including sound emitting means operatively connectedto said signal-processing means and actuated by said third signal. 9.The arrangement as defined in claim 2 including picture recording meansfor recording the visual appearance of the interior of said space. 10.The arrangement as defined in claim 2 including visual indicating meansoperatively connected to said signal processing means and actuated bysaid third signal.
 11. The arrangement as defined in claim 2 includingsignal-transmitting means connected to said third signal-processingmeans for transmitting said third signal to a location remote from saidspace.
 12. The arrangement as defined in claim 2 including manuallyoperable switching means within said space and linked to saidsignal-processing means, said signal-processing means emitting anundelayed signal when said switching means is manually actuated.